1. Field of the Invention
This invention relates to combinations employing pressurized communications conduit and a system for checking the pressure of the pressurized fluid therewithin. More particularly, this invention relates to such a communication system for checking the pressurized fluid within communications conduit and employing a device that will allow full pressurizing flow, yet block full reverse flow while still allowing a minute reverse flow that is still enough to check the pressure.
2. Description of the Prior Art
A wide variety of prior art combinations have been employed to allow pressurizing a communications conduit yet provide means for checking the pressure therewithin at a point that is more readily accessible from the surface of the earth. The pressurized conduit may be elevated on poles or the like, or it may be buried beneath the surface of the earth. To enable checking the pressure within the conduit, a check point, such as a smaller conduit and valve will be in communciation with the larger communication conduit. Not infrequently, the smaller conduit will be torn away, broken, or otherwise develop leaks and cause back flow that would drain the pressurized fluid from the communications conduit. Conventions check valves close to the communications conduit could prevent back flow but interferred with testing the pressure. To solve both problems, the prior art has seen relatively complex, expensive apparatus employed. Broadly, for example, there have been safety devices for effecting non return flow of oil in a transformer; electronically openable valves could be opened responsive to a signal transmitted by the repairman on expensive pieces of electronic equipment; employing two smaller conduits to the surface with a pumping means to pressurize via one line to open the other for checking the pressure; and devices that open responsive to pressure supplied from the free end of the smaller conduit; and other similar devices. As can be seen, the prior art devices have been objectionable that they were expensive, required a second piece of apparatus to be carried by the repairman in addition to the pressure testing device, required pressurizing of the lines such that an inaccurate pressure reading was obtained, required a plurality of conduits or the like.